Signal transfer system of programmable controller

ABSTRACT

Disclosed is a signal transfer control system of a programmable controller for transferring I/O signals between the PC and an external device. An I/O unit (26) includes an I/O signal region (1) for storing I/O signals transferred or received to or from an external device, and mapping data (2) for defining the mapping of the I/O signal region (1). Further, a RAM (23) of the PC includes point data (3) for defining the address to which I/O signals from the mapping data (2) are to be transferred, and an I/O data region (4) for storing the I/O data. Input signals are stored in the I/O signal region (1) and each of the I/O signals is mapped by the mapping data (2), and the point data (3) determines the address to which each of the mapped input signals is to be transferred. Namely, the addresses to which the input signals are to be transferred are determined by the mapping data (2) and the point data (3), and the input signals are then transferred to the I/O data region (4). Conversely, the input signals are transferred from the I/O data region (4) to the I/O signal region (1) by the point data (3) and the mapping data (2). Therefore, even if the arrangement of these I/O signals is changed, the change can be dealt with by changing the point data or the mapping data, without the need to change a sequence program.

TECHNICAL FIELD

The present invention relates to a signal transfer system of aprogrammable controller (PC) used to control a machine tool, and morespecifically, to a signal transfer system of a PC by which thearrangement of I/O signals can be easily changed.

BACKGROUND ART

Programmable controllers (PCs) are widely used for the control, etc. ofa machine tool. The programmable controller (PC) includes a programmablemachine controller (PMC) incorporated in a numerical control apparatusand a programmable controller arranged independently of the numericalcontrol apparatus.

Both of these PCs are interposed between the machine tool and thenumerical control apparatus, to enable many I/O signals to betransferred therebetween, but the arrangement of these I/O outputsignals in the numerical control apparatus is different from that at theentrance of the PC. More specifically, the numerical control apparatushas a predetermined standard arrangement of I/O signals by which itadjusts itself to many kinds of machine tools, but each machine tooldoes not always use all of the I/O signals of the numerical controlapparatus and thus has a different arrangement of the I/O signals.Accordingly, when a sequence program of the PC is created, thearrangement of these signals must be changed.

Nevertheless, when the number of the I/O signals is increased, asequence program having a considerable number of steps must be createdto change the arrangement of these signals, which imposes a burden uponthe creation of the program. Further, when a detailed specification of amachine tool is changed, the sequence program must be changed, whichmakes the sequence program incompatible and causes maintenance problems.

DISCLOSURE OF THE INVENTION

Taking the above into consideration, an object of the present inventionis to provide a signal transfer control system of a PC by which thearrangement of I/O signals is easily changed.

To solve the above problem, according to the present invention, there isprovided a signal transfer control system of a programmable controllerfor transferring I/O signals between the PC and an external device,which comprises an I/O signal region for storing the I/O signal to theexternal device, mapping data for defining the mapping of the I/Osignals, point data for defining the addresses to which the I/O signalsare to be transferred, based on the mapping data, and an I/O data regionfor storing the I/O signals.

The input signals are stored in the I/O signal region and each of theI/O signals is mapped by the mapping data and the point data determinesthe address to which each of the mapped input signals is to betransferred. Namely, the addresses to which the input signals are to betransferred are determined by the mapping data and the point data, andthe input signals are then transferred to the I/O data region.Conversely, the output signals are transferred from the I/O data regionto the I/O signal region by the point data and the mapping data.

Therefore, even if the arrangement of these I/O signals is changed, thechange can be dealt with by changing the point data or the mapping datawithout the need to change a sequence program.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram explaining the change of the arrangement of I/Osignals of a signal transfer control system of a PC; and

FIG. 2 is a block diagram of the entire hardware of a numerical controlapparatus (CNC) embodying the present invention.

BEST MODE OF CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to drawings.

FIG. 2 is a block diagram of the entire hardware of a numerical controlapparatus (CNC) embodying the present invention. A programmable machinecontroller (PMC) 20 is incorporated in a numerical control apparatus(CNC) 10, and a processor 11, which controls the numerical controlapparatus (CNC) 10 as a whole, reads out a system program stored in aROM 13, through a bus 19, and controls the numerical control apparatus(CNC) 10 as a whole according to the system program.

A shared RAM 12 enables the CNC 10 to transfer or receive data to orfrom the PMC 20, and thus the CNC 10 and PMC 20 transfer data to eachother through the shared RAM 12. Further, the shared RAM 12 stores dataneeded to allow a simultaneous access by the CNC 10 and PMC 20.

A RAM 14 stores temporary calculation data, display data, and the like.A CMOS 15 is composed of a non-volatile memory which stores amounts oftool correction, amounts of pitch error correction, machining programs,parameters, and the like, and these data are maintained even after apower supply to the numerical control apparatus (CNC) 10 is cut off,because the CMOS is supplied with power from a not shown battery and isa non-volatile memory. Further, the CMOS 15 stores parameters and thelike needed by the PMC 20.

A graphic control circuit 16 converts digital data such as the presentposition of each axis, an alarm, parameters, image data, and the likeinto image signals, and outputs same to a display unit 31 of a CRT/MDTunit 30, to be displayed thereat. Parameters, ladder diagrams and thelike of the PMC 20 side can be also displayed at the display unit 31.Data at this time is supplied from the PMC 20 through the shared RAM 12.

An interface 17 receives data from the key board 32 in the CRT/MDI unit30 and supplies same to a processor 11. Further, data to the PMC 20 canbe input through the keyboard 32 and supplied to the PMC 20 through theshared RAM 12.

An interface 18 for external units is connected to an external unit 40such as a paper tape reader, paper tape puncher, paper tapereader/puncher, printer, and the like, and machining program can be readfrom the paper tape reader, and a machining program edited in thenumerical control apparatus (CNC) 10 can be output to the paper tapepuncher.

The processor 11 is connected to the elements such as the shared RAM 12,ROM 13, and the like through the bus 19.

Note, an axis control circuit for controlling servo motors and the like,a servo amplifier, a spindle control circuit, a spindle amplifier, aninterface for a manual pulse generator and the like, are not shown inthe figure.

The programmable machine controller (PMC) 20 is provided with aprocessor 21 for the PMC, which is connected to the shared RAM 12through a bus 25, and the shared RAM 12 is connected to the bus 19 ofthe CNC 10.

Further, a ROM 22 is connected to the bus 25, and stores a managementprogram and sequence program for controlling the PMC 20. Although thesequence program is generally created by the use of a ladder language,it is sometimes created by a high-level language such as PASCAL or thelike. Further, sometimes a ROM cassette interface is provided in placeof the ROM 22, and a ROM cassette storing the sequence program isconnected to the ROM cassette interface. With this arrangement, thesequence program can be easily upgraded and changed.

Further, a RAM 23 is connected to the bus 25 and stores an I/O signal,and the content thereof is rewritten as the sequence program isexecuted.

An I/O control circuit 24 is connected to the bus 25, converts an outputsignal stored in the RAM 23 to a serial signal, and transfers same to anI/O unit 26. Further, the I/O control circuit 24 converts a serial inputsignal from the I/O unit 26 to a parallel signal and transfers same tothe bus 25. The signal is stored in the RAM 23 by the processor 21.

The processor 21 receives command signals such as an M function signal,T function signal and the like from the CNC 10 through the shared RAM12. These command signals are temporarily stored in the RAM 23,processed according to the sequence program stored in the ROM 22, andthen output to the I/O unit 26 through the I/O control circuit 24. Theseoutput signals control hydraulic units, pneumatic units, and magneticunits of a machine tool.

Further, the processor 21 receives input signals such as a limit switchsignal on the machine side, a signal from an operation switch on amachine control panel and the like from the I/O unit 26, and temporarilystores these signals in the RAM 23. Input signals not required to beprocessed by the PMC 20 are transferred to the processor 11 through theshared RAM 12; other signals are processed by the sequence program and apart thereof output to the CNC, and the remaining signals are output asan output signal from the I/O unit 26 to the machine tool through theI/O control circuit 24.

Further, the sequence program can include commands for controlling themovement and the like of each axis, and when read by the processor 21,these commands are transferred to the processor 11 through the sharedRAM 12, to control the servo motors. The spindle motors and the like maybe similarly controlled by commands from the PMC.

Furthermore, the sequence program stored in the ROM 22 and the I/Osignals stored in the RAM 23 may be displayed at the display unit 31 ofthe CRT/MDI unit 30.

Also, the sequence program of the ROM 22 may be output to the printerconnected to the interface 18, through the shared RAM 12 and bus 19. Aprogram creation device may be connected to the interface 18, a sequenceprogram and the like created by the program creation device may betransferred to the RAM 23, and the PMC 20 may be operated by thesequence program in the RAM 23.

The arrangement of the I/O signals stored in the above RAM 23 isdifferent from that of the I/O signals in the I/O unit. Morespecifically, the I/O signals in the RAM 23 have a standard arrangementbecause the RAM 23 transfers or receives signals to or from the CPU 11through the shared RAM 12, whereas the arrangement of the I/O signals inthe I/O unit 26 is determined depending on the arrangements of the limitswitches, actuators and the like in the machine tool. Therefore, whenthe I/O unit 26 transfers or receives the I/O signals to or from the RAM23, the arrangement of the I/O signals must be changed.

FIG. 1 is a diagram explaining the change of the arrangement of I/Osignals in a signal transfer control system of a PC according to thepresent invention. The I/O unit 26 includes an I/O signal region 1 forstoring I/O signals from the machine tool and mapping data 2, andfurther, the RAM 23 in the PMC 20 includes point data 3 and an I/O dataregion 4 for storing I/O signals as I/O data.

Since the arrangements of output signals and input signals are changedin the same manner, except that the direction of the former signals isopposite to that of the latter signals, only the change of the inputsignals will be described. Each 8 points of input signals from themachine tool are put together as one bite, and are stored in the I/Osignal region 1. Note, some signals may not be used, and in this case,some bits in the 1 bite are not occupied.

Then, 0 is allocated to an input signal DIA stored in the address 0 ofthe I/O signal region 1 by the mapping data 2, and since 3 has beenallocated to the address 0 of the point data, the input signal DIA istransferred to the address 3 of the I/O data region 4. In the same way,an input signal DIB is transferred to the address 2, an input signal DICis transferred to the address 4, and an input signal DID is transferredto the address 0 of the I/O data region 4, respectively.

As described above, when the mapping data and the point data are used,even if the arrangements of the I/O signals in the I/O unit 26 and theRAM 23 are changed, the sequence program and the like do not need to bechanged because only the mapping data or the point data are changed. Thearrangement of the outputs signals can be changed in the same way.

Although the I/O signals are transferred in a bite unit in the abovedescription, they can be transferred in a bit unit, but in this case,the mapping data and the point data must by arranged in the bit unit.

Further, although the I/O unit is incorporated in the numerical controlapparatus, it may be provided in the controller of the machine tool.

Furthermore, although the PC is described as a programmable machinecontroller (PMC) incorporated in the numerical control apparatus, it maybe a programmable controller (PC) provided independently of thenumerical control apparatus.

As described above, according to the present invention, since thearrangement of the I/O signals is changed by using the mapping data andthe point data, the arrangement of the I/O signals can be easily changedwithout the need to change the sequence program.

We claim:
 1. A signal transfer control system for transferring I/Osignals between a programmable controller and a machine tool, saidsystem comprising:an I/O unit operatively connected to the machine tooland including an I/O unit memory having I/O signal regions capable ofstoring the I/O signals and mapping data regions corresponding to saidI/O signal regions and capable of storing mapping data to identifyaddresses of point data to be used in transfer of I/O signals incorresponding of said I/O signal regions; and a programmable controllerincludinga programmable controller memory having point data regions atpoint data addresses capable of storing point data to identify addressesto which the I/O signals are to be transferred and I/O data regionscapable of storing the I/O signals at I/O signal addresses, and acentral processing unit operatively connected to transfer an I/O signalfrom an I/O signal region of said I/O unit memory to an I/O data regionof said programmable controller memory by, first, retrieving an I/Osignal from an I/O signal region of said I/O unit memory and retrievingcorresponding mapping data from a corresponding mapping data region ofsaid I/O unit memory, second, retrieving point data from a point dataregion at a point data address identified by the mapping data retrievedfrom the corresponding mapping data region of said I/O unit memory, andthird, storing the retrieved I/O signal in an I/O data region of saidprogrammable controller memory having an I/O signal address identifiedby the point data retrieved from the point data region of saidprogrammable controller memory.
 2. A signal transfer control systemaccording to claim 1, wherein said programmable controller memory isprovided in a RAM.
 3. A signal transfer control system according toclaim 2, wherein said programmable controller is a programmable machinecontroller operatively connected for control by a numerical controlapparatus.